1. Technical Field
This invention relates in general to the patterning of nanoscopic materials, films, fabrics, layers, and articles and in particular to the patterning of nanowires, nanotubes, nanoclusters and mixtures of nanotubes and nanowires.
2. Discussion of Related Art
Nanowires are used for electronic conductors and semiconductors as well as for light emitters, sensors, including bio sensors, etc.
There are numerous methods of creating nanowires and there are many materials from which nanowires can be made, including, but not limited to: semiconductors such as silicon and metals as described below. Nanowires of silicon can be created by deposition of a silicon oxide film through the openings of a patterned resist film, reactive ion etching (RIE), removal of the oxide and etching of the silicon, see e.g., Namatsu, H., et al., “Fabrication of thickness-controlled silicon nanowires and their characteristics,” J. Vac. Sci. Technol. B 13 (6), 1995. Silicon nanowires can be fabricated by AFM to realize lithography patterns on Si surfaces after an etching step (Legrand, B., et al., “Silicon nanowires with sub 10 nm lateral dimensions: From atomic force microscope lithography based fabrication to electrical measurements,” J. Vac. Sci. Technol. B 20(3)). Iron magnetic nanowire arrays can be created by using a shadow mask for an iron evaporator and depositing iron, see Tulchinsky, D. A., et al., “Fabrication and domain imaging of iron magnetic nanowire arrays,” J. Vac. Sci. Technol. A 16(3), 1998. Silver silicate nanowire arrays can be created by direct current electrodeposition into nanochannels, see e.g., Peng, X. S., et al., “Electrochemical fabrication of ordered Ag2S nanowire arrays,” Materials Research Bulletin 37, 2002, 1369-1375. Li, C. P., et al. report gold-wrapped silicon nanowires with ohmic contacts, see “Silicon Nanowires Wrapped with Au Film,” J. Phys Chem. B 2002, 106, 6980-6984. Cu—Co, Co—Ag and Fe—Ag nanowires can be fabricated by electrodeposition as reported by Wang, Y. W., et al., “Fabrication of Ordered Ferromagnetic Alloy Nanowire Arrays and their Magnetic Property dependence on Annealing Temperature,” J. Phys/Chem. B 2002, 106, 2502-2507. Nickel and bismuth nanowires can be fabricated by electrodeposition, see Yin, A. J., et al., “Fabrication of highly ordered metallic nanowire arrays by electrodeposition,” Applied Physics Letters, Vol. 79, No. 7, 2001. Nanowires of gallium arsenide can be fabricated in arrays via chemical vapor deposition in nanochannels of anodic alumina plates, see Zhang, J., et al., “Fabrication and photoluminescence of ordered GaN nanowire arrays,” Journal of Chemical Physics, 115 (3), 5714-5717, 2001. Such nanowire arrays can be utilized for their photoluminescence properties. Titanium oxide nanowires can be used for photoluminescence as well, see e.g., Lei, Y., et al., “Fabrication, characterization, and photoluminescence properties of highly ordered TiO2 nanowire arrays,” J. Mater. Res., Vol. 16 No. 4, 1138-1144, 2001. TiO2 nanowire arrays can be fabricated by anodic oxidative hydrolysis, see Lei, Y., et al., “Fabrication, characterization and Raman study of TiO2 nanowire arrays prepared by anodic oxidative hydrolysis of TiCl3,” Chemical Physics Letters 338 (2001) 231-236. Zinc oxide nanowires arrays can be patterned in a one step electro-chemical deposition technique based on an ordered nonporous alumina membrane. See Zheng et al., “Fabrication and optical properties of large-scale uniform zinc oxide nanowire arrays by one-step electrochemical deposition technique,” Chemical Physics Letters 363 (2002) 123-128. Silicon carbide nanowires can be fabricated using catalysts. See Deng et al., “Synthesis of silicon carbide nanowires in a catalyst-assisted process,” Chem. Phys. Letters 356 (2002) 511-514.
Nanowires can be useful as other than electronic conductors, e.g., nanowires can be used for their phononic effects, see Ciraci, S., et al., “Quantum effects in electrical and thermal transport through nanowires,” J. Phys. Condens. Matter 13 (2001) R537-R568.
Nanowires can be formed into arrays for thermometry, see Pekola, J. P., et al., “Thermometry by Arrays of Tunnel Junctions,” Phys. Rev. Lett. 73, 2903.
Investigators have created nanowires out of thin, contiguous films via lithography, i.e., they have taken contiguous films and removed much of the material, leaving only very thin strips, i.e., nanoscale wires. The material from which the wires were created sat upon a sacrificial layer above a substrate and then the sacrificial material is underetched to leave suspended nanowire. See Pescini, L., et al., “Suspending highly doped silicon-on-insulator wires for applications in nanomechanics,” Nanotechnology 10 (1999) 418-420.
The use of nanowire technology in sensors allows for speedier operation and radiation hardness, while maintaining compatibility with standard silicon processing and the intrinsic sensitivity to their environment creates an increasing industrial demand.
Other uses of nanowire devices include as a resonator probed by a net work analyzer and capacitance coupling (see Blick, R. H., et al., “Nanostructured silicon for studying fundamental aspects of nanomechanics,” J. Phys. Condens. Matter 14 (2002) R905-R945), polymer cantilevers, mechanical oscillators for signal transduction, filtering and mixing, nanoscale actuators, suspended nanowire bridges, Coulomb blockade thermometers, etc. (see Pekola, J. P., et al., “Thermometry by arrays of tunnel junctions,” Phys Rev. Lett.).
Current technology does not allow for facile fabrication of large scale nanoscopic nanowire devices; there is therefore a need in the art for a method of creating structures of patterned nanowire fabrics.